Electrolytic process



UNITED STATES PATENT OFFICE.

FREDERICK S. WOODWARD, OF RICHMOND HILL, NEW YORK.

ELECTROLYTIC PROCESS.

No Drawing. Application filed July 25,

To all whom it may concern:

Be it known that I, FREDERICK S. WOOD- WARD, acitizen of the United States, and a resident of Richmond Hill, Long Island, New York, have invented a new and useful Electrolytic Process, of which the following is. a specification. My invention relates to electro-deposltions of metals for plating operations or for production of pure metals electrolytically, and is especially applicable to copper deposition. The object of the invention is to avoid the necessity of using as anodes the material which is to be deposited, thus being able to secure the desired metal indi rectly from cheaper sources of supply.

According to my invention I plate or deposit the copper from an electrolytic bath originally made up, for example, of an aqueous solution of copper sulfate and free sulfuric acid. Insoluble anodes are employed, such as lead, or other suitable material not soluble in the bath. The use ,of insoluble anodes results in rapid depletion of the copper content of the bath, as copper is deposited from the copper sulfate solution and free sulfuric acid is produced as a result. This free sulfuric acid tends of course to increase as the copper content diminishes. The invention therefore proved aregenerating or rejuvenating process for maintaining the proper proportions of copper sulfate and free acid in the bath.

This rejuvenating of the sulfate solution may be accomplished in various ways. The

addition of copper sulfate directly to the depleted solution would'not avoid the continued increase of free sulfuric acid, and therefore according to my invention the rejuvenation includes at the same time the provision of a neutralizing action for the increment of free sulfuric acid arising in the depositing operation. This may be accomplished for example by the introduction of copper sulfate and a base or salt capable of forming an insoluble sulfate without contaminating the solution. Examples of such bases or salts are calcium oxid and calcium carbonate. Instead of adding copper sulfate and a separate base or salt for precipitating the insoluble sulfate, I may neutralize the increment of free sulfuric acid by a copper compound capable of. reacting therewith to produce within the deposition ofmetal.

Specification of Letters Patent. A I Patented Apr. 12, 1921.

1919. Serial no. 313,329.

bath additional quantities of copper sulfate. Examples of such compounds would be oxids and carbonates of copper. In the selection of suitable copper compounds care is taken that undesirable soluble by-products are avoided. In the use of copper oxid for example, the setting free of another acid radicalis avoided, whereas carbonates are advantageous as the resulting acid radical set free is gaseous and does not remain in solution to contaminate the bath. This added substance may be relatively cheap and need not be particularly pure. Minelrflrls such as malachite and azurite are suita e. V 1

Where an insoluble sulfate is produced from theexcess of free sulfuric acid suit able procedure is followed to remove this from the bath'before returning the bath to anode insoluble in the bath, and neutralize ing only the resulting increment of free acid while restoring the bath to normal I strength and condition.

2. An electrolytic'process comprising depositing copper from an acid bath with an anode insoluble in the bath, removing the depleted bath, introducing into the depleted bath chemical substance capable of and in amount suitable. for neutralizing only the resulting increment of free acid and restoring the strength and'constitution of the bath to normal, and returning the b serve in the deposition of metal. 7

3, An electrolytic process comprising depositing copper from acid solution of copper sulfate in water, with'the use of an inath to again soluble anode, withdrawing the spent solution from the depositing operation, treating the spent bath chemically to restore the copper sulfate tonormalstrength and neutralize only the increment of free sulfuric'acid,

and returning the restored bath for further FREDERICK s. woonw RD; 

